And about the OP, I agree that some use should be given to clay apart from white necromancy (supposing it doesn't already have an use that we don't know).
Otherwise, it's a totally useless item for the majority of characters (it can be argued that specialized items like a fletchery set or a cooking set are also useless for the majority of characters, but any character can learn to use them in the game - they may not want to invest resources in doing so, but that's a different matter).